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Posted: 5/3/2013 7:41:07 AM EDT
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Once or twice a month at the range a member will be shooting his AR15 without incident. At some point (we are still collecting information) a live round works its way into the gas keyway. The bolt is closed half way, jamming the round upward so hard that nothing can be moved. The charging handle won't move because the nose of the bullet is pressing against it. The bolt won't move due to the round stuck in the keyway. What kind of failure is this?
One possibility is that the new round has been dropped into the ejection port with the rifle lying on its side. The shooter then lets the bolt fly forward with the rifle still on its side. Thanks, WhiteFox |
| ITs a mag issue, happens all the time with wornout magazines. when the carrier moves back and extracts the empty case one round "pops" out of the mag. As the carrier moves forward it strips another round from the mag, so now there are two rounds trying to be chambered. One of the rounds gets pushed above the bold and you have the round over bolt malfunction. MOrtaring the rifle is the usual answer. |
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Thanks to all for your comments. And thanks to occasionalvisitor for pointing out the obvious. Bad magazines make the most sense to me also - second to not following the manual of course. The next-to-last round failure is very common with 1911's, and almost always it happens because the mag spring is weak, the mag follower is too slick, the feed lips aren't right or all 3 together.
So many magazine makers, so few good magazines. Plastic magazines have seemed questionable to me for the same reason. I'm sure they are great for a couple of uses or to save weight. Many AR owners also don't know they may have to "adjust" their mags if the rounds don't stack and release evenly. Magpul has solved many of the problems with their excellent followers. U toob videos are calling this jam "brass over bolt". All of them agree that the bolt has to be pushed back, but none of them make a guess on how it happens. As I said, I never heard of it until just recently. Not that it means much. I'll stick with the bad mag theory for now. WhtieFox |
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